Mechanical support of transient recovery voltage capacitor within circuit breaker low pressure tank

ABSTRACT

A gas blast circuit breaker consists of a generally flattened spherical configuration in which the circuit breaker interrupters are disposed along the major axis of the tank which is at ground potential. Transient voltage recovery capacitors, which are electrically connected between the transmission line coming into the circuit breaker and ground on the line side of the circuit breaker, are physically mounted within the tank at outer diametrical regions of the tank between the end of the interrupters and the interior surface of the tank.

United States Patent [1 1 McConnell Sept. 2, 1975 MECHANICAL SUPPORT OF TRANSIENT 3,091,678 5/1963 Leeds 200/148 B RECOVERY VOLTAGE CAPACITOR 3,526,734 9/1970 McKeough 200/148 R WITHIN CIRCUIT BREAKER LOW PRESSURE TANK Primary ExaminerRobert S. Macon Attorney, Agent, or FirmOstrolenk, Faber, Gerb &

[75] Inventor: Lorne D. McConnell, Chalfont, Pa. soffen [73] Assignee: I-T-E Imperial Corporation, Spring House 57 ABSTRACT [22] Filed: Sept 1973 A gas blast circuit breaker consists of a generally flat- [21] A No. 398,869 tened spherical configuration in which the circuit breaker interrupters are disposed along the major axis of the tank which is at ground potential. Transient [52] US. Cl z 200/148 B, 20g/l45 voltage recovery capacitors, which are electrically CI. connected between the transmission line coming into [58] held of Search 200/148 148 148 the circuit breaker and ground on the line side of the 200/148 145 circuit breaker, are physically mounted within the tank at outer diametrical regions of the tank between [56] References C'ted the end of the interrupters and the interior surface of UNlTED STATES PATENTS the tank 2,921,168 1/1960 Forwald 200/148 B 3,045,086 7/1962 Leeds et al 200/148 B 7 Clams 2 Dramng Flgures f 37 as, as

2' 36 a} p 77 52 J; 527 f? l l I I l l i n I 5/ I F a 27 g 5 z 3 54 55 MECHANICAL SUPPORT OF TRANSIENT RECOVERY VOLTAGE CAIACI'IOR WI'IIIIN CIRCUIT BREAKER LOW PRESSURE 'IANII.

RELATED APPLICATIONS This application is related to copending application Ser. No. 398,871, filed Sept. I9, 1973, entitled CONTACT STRUCTURE FOR HIGH VOLTAGE GAS BLAST CIRCUIT INTERRUPTER, in the name of H. Aumayer; and 398,868, filed Sept. 19, I973, entitled GAS CIRCUIT BREAKER INSULATING TUBE SUPPORT AND HIGH PRESSURE VESSEL, in the name of G. P. Guaglione et al., both of which are assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to high voltage gas blast circuit interrupters, and more specifically relates to the novel mounting of a transient recovery voltage capacitor within a dielectric gas filled tank which is at ground potential. High voltage gas blast circuit breakers are well known to the art. One type of circuit breaker is the socalled dead tank circuit breaker shown in US. Pat. No. 3,526,734, issued Sept. 1, I970, entitled DEAD TANK GAS BLAST CIRCUIT BREAKER WITI-I INTER- RUPTER STRUCTURE IMMERSED IN LOW PRES- SURE OF DEAD TANK, in the name of D. H. McKeough, and assigned to the assignee of the present invention. As shown in US. Pat. No. 3,526,734, the circuit breaker generally consists, for each phase, ofa flattened spherical tank which contains circuit interrupters therein which are connected to terminal bushings which enter and leave the tank. The tank is then filled with sulfur hexafluoride or some other low dielectric gas under a relatively low pressure. such as 3 atmospheres. The interrupters are connected to a source of relatively high pressure, such as sulfur hexafluoride at atmospheres, such that when the interrupters are operated, a high pressure gas flows through the interrupting contacts to assist in the interruption of the are drawn between the interrupter contacts.

It is well known that the transient recovery voltage on the interrupters or on the circuit breaker can be con trolled by an appropriate dimensioned capacitor which is connected between the phase conductors coming into the circuit breaker and ground. Capacitors of this type and their function is generally described in US. Pat. No. 3,383,519, issued May 14, I968.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, a transient recovery voltage capacitor is mounted within the circuit breaker tank and on the generally outer regions of the tank which contain sufficient open volume for physically receiving such capacitors without creating breakdown dangers between the capacitor and the in terrupting components. Thus. the generally flattened spherical tank structure permits the novel utilization of space and the capacitors can be connected directly to the grounded tank at one end and to the line terminat,

at the other end. Moreover, since the capacitors are mounted within the sulfur hexafluoride gas which is at elevated pressure (hereinbefore termed a low pressure, but in fact a pressure of about 3 atmospheres which is low only compared to the high pressure reservoirs of the breaker which may be at l5 atmospheres), the sulfur hexafluoride dielectric characteristics improve the insulation between the capacitor and the other components within the circuit breaker and further permit the use of smaller capacitor components.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view partly in section of a circuit breaker which contains transient voltage recovery capacitors mounted within the tank in accordance with the present invention.

FIG. 2 is a partly schematic side plan view of the circuit breaker of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, there is shown, in partial section, one phase of a high voltage circuit breaker which incorporates the present invention, as will be later described. The circuit breaker of FIG. 1 can, for example, be rated at 230,000 volts and at 63,000 amperes. conventionally, the breaker will be a threephase breaker and two other and identical phases to the one shown in FIG. 1 will also be provided.

In general, the circuit breaker phase of FIG. 1 is contained within a generally flattened spherical metallic tank 10 which is supported on metallic frame angle members II and 12. Angles l1 and 12 are suitably reinforced and extend rearwardly and support additional tanks to tank 10, which are spaced from the tank 10 and disposed generally parallel to tank 10 and constitute the other phases of the circuit breaker. The metallic tank 10 is a grounded housing and the circuit breaker shown herein for purposes of illustrating the invention is shown in a dead tank configuration.

The terminal bushings for the breaker may be of any standard type and are shown for illustration herein as including the bushings 13 and 14 which extend through cylindrical shrouds l5 and 16, respectively, which are appropriately welded or otherwise secured to the tank and are sealed relative to the interior of the tank. Gas barriers l7 and 18, respectively, are provided to prevent the leakage of gas from tank 10. Thus, tank I0 is filled with sulfur hexafluoride gas (or a gas mixture which includes sulfur hexafluoride) at a pressure of about 3 atmospheres. For purposes of the invention, any dielectric gas at any appropriate pressure could be used. For the embodiment described herein, the gas pressure within tank 10 will be designated a relatively low pressure.

Each of the bushings l7 and 18 is further associated with current transformers l9 and 20, respectively, which may also be of any desired construction.

A grounded flat support platform 21 is contained within the tank 10 and is supported from the bottom of tank It) by welded support members, such as bolts 22 and 23 and others not shown. Platform 2l sits on leveling nuts, such as nuts 24 and 25, respectively, of the support bolts. The platform 21 then serves as a level mount for the circuit interrupter equipment to be contained within tank 10. In the case of the breaker shown in FIG. 1, four interrupters are to be connected in series with one another to define the circuit breaker voltage rating of 230 KV. Platform 21 supports two spaced hollow tubular insulation support members 26 and 27, respectively, which further serve the purpose of high pressure gas reservoirs as is more fully described in copending application Ser. No. 398,868, referred to above.

Each of the insulation support members 26 and 27 support, at their tops, respective blast valve housings 28 and 29 which, in turn, support series-connected interrupter units 30-31 and 32-33, respectively. Each of the interrupter units contains a pair of interrupter contacts which are simultaneously opened in the presence of a blast of gas which assists in extinguishing the arc. It is to be noted that the tubes 26 and 27, blast valve housings 28 and 29, and interrupters 30 to 33 are mechanically supported solely from the platform 21 and that none of these components are supported from the bushings l3 and 14 or intermediate supports for the interrupters 31 and 32.

The top of interrupter 30 is electrically connected to the stud 35 of terminal bushing 13 through a flexible connection, which will be later described. The connec tion between the top of interrupter 30 and stud 35 is then covered by a corona shield 36.

The bottom of interrupter 30 is then connected through housing 28 to the bottom of interrupter 31. The top of interrupter 31 is connected through flexible shunts 36a to the top of interrupter 32 with the tops of interrupters 31 and 32 and flexible connectors covered by corona shields 37 and 38, respectively.

The bottom of interrupter 32 is then connected through the blast valve housing 29 to the bottom of interrupter 33. The top of interrupter 33 is in turn connected to the stud 39 of bushing 14 by flexible connectors, such as flexible connectors 40 and 41. The connection previously referred to between interrupter 30 and stud 35 incorporates flexible connectors, such as the connectors 40 and 41. The connection to stud 39 is then covered by the corona shield 42.

FIG. 1 also shows voltage distributing impedances 43 and 44 connected across interrupters 30 and 33, respectively. Note that any suitable arrangement of parallel-connected capacitors or resistors could be used across the various interrupters 30 to 33 in order to assure appropriate distribution of steady state and transient voltages across the series-connected breaks.

FIG. 1 illustrates the provision of transient recovery voltage capacitors 50 and 51 which are to be connected from either of the line sides of the breaker to ground. It will be noted that the flattened elliptical shape of tank makes available free space in the outer central regions of the tank so that these capacitors can be mounted within this space without interference with the operation of the breaker or without interference with the dielectric integrity of the breaker.

In the above, the tank 10 was described as a flattened spherical tank. The nature of the flattening of the tank is generally described in connection with FIG. 2 which shows the tank 10 and further schematically illustrates the capacitor 51 which is in the side of the tank 10 which is viewed in FIG. 2.

It will be noted from FIG. 1 that the upper terminals of each of capacitors 50 and 51 are connected by relatively rigid conductors 52 and 53 to the tops of inter rupters 30 and 33, respectively, and are directly and solidly connected to the bushing studs 35 and 39, respectively. The bottoms of capacitors 50 and 51 are then mechanically and electrically connected to the tank wall 10 by the support and grounding brackets 54 and 55, respectively.

The transient recovery voltage across the breaker is then controlled by the capacitors 50 and 51 in the manner generally set forth in US. Pat. No. 3,383,5l9, it

being noted that each of capacitors 50 and 51 may have a value of approximately 0.0025 microfarads or any other desired value selected by the circuit designer.

The interior of the insulation reservoirs 26 and 27, which communicate with the blast valve housings 28 and 29 and thence to the interrupters 30 to 33 is at a relatively high pressure, such as 15 atmospheres of the same dielectric gas which fills tank 10.

The major pressure source for the breaker is an elongated cylinder 60 which is filled with gas at high pressure and which may be covered with a heater blanket 61 to ensure that the gas temperature will always be sufficiently high to maintain it in a gaseous state. A protective shroud 62 covers the cylinder 60 (which may extend the full length of all of the phases of the breaker), with portholes such as porthole 63 being available to permit maintenance of the cylinder 60 and the blanket 61. A suitable gas control system, which need not be described to understand the present invention, provides suitable gas conduits and gas controls to conduct gas from the cylinder 60 through the conduit 64 which passes through a sealing plug 65 in tube 66 which is secured to tank 10.

The high pressure conduit 64 then extends through a T-shaped member and into conduits 67 and 68 as generally outlined by the arrows, in FIG. 1, such that high pressure gas is admitted to the interior of insulation reservoirs 26 and 27. As will be later described, this gas in normally sealed at the blast valve housings 28 and 29 and high pressure gas is released through the interrupters 30 and 33 and into low pressure tank 10 only when the contacts of the interrupters are operated.

A suitable mechanical operating mechanism (not shown herein) is provided to mechanically actuate crank arms, such as crank arm- 70 associated with tube 26, which drive operating rods which extend through the center of support tubes 26 and 27 and upwardly to blast valve housings 28 and 29. Similar crank arms will be associated with each of the other interrupters of each phase of the breaker. Any conventional operating mechanism, such as a spring operated mechanism or hydraulically operated mechanism is then connected to each of the crank arms so that all blast valves and contacts can be simultaneously operated to either open or close all interrupter contacts.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privelege or property is claimed are defined as follows:

1. In a high voltage circuit breaker:

a grounded support tank filled with dielectric gas at some pressure greater than atmospheric pressure; said tank having a generally flattened spherical shape; said tank having an interior bottom and a vertical axis;

circuit interrupter support means secured to said interior bottom of said tank and being generally laterally symmetrically disposed around said vertical axis of said tank;

circuit interrupter means supported on the top of said support means and electrically insulated from said tank; said circuit interrupter means including at least four series-connected interrupters, and voltage distributing impedances disposed within said tank and connected in parallel with at least selected ones of said at least four series-connected interrupters;

first and second terminal bushings disposed symmetrically relative to said vertical axis of said tank and extending through and secured to laterally displaced regions of the top of said tank; said terminal bushings having conductive studs electrically insulated from said tank and electrically connected to said circuit interrupter means;

and first and second capacitors for control of transient recovery voltage physically mounted within opposite side regions of said tank and laterally displaced from said circuit interrupter support means and said circuit interrupter means;

each of said capacitors having first and second terminals; said first terminal of each of said capacitors being disposed adjacent to and being electrically connected to respective interior portions of said tank; said second terminal of each of said capacitors being electrically connected to said conductive studs of said first and second terminal bushings, respectively.

2. The circuit breaker of claim 1 wherein said first and second capacitors are each elongated tubular bodies which are vertically disposed within said tank.

3. The circuit breaker of claim 1 wherein said first and second capacitors have a value to appreciably lower the initial rate of rise of the recovery voltage transient imposed across said interrupter means following a fault current interruption.

4. The circuit breaker of claim 1 wherein said circuit interrupter support means includes at least two parallel vertical tubular insulation pedestals which are spaced from one another along the major horizontal diameter of said tank.

5. The circuit breaker of claim 2 wherein said first and second capacitors have a value to appreciably lower the initial rate of rise of the recovery voltage transient imposed across said interrupter means following a fault current interruption.

6. The circuit breaker of claim 2 wherein said circuit interrupter support means includes at least two parallel vertical tubular insulation pedestals which are spaced from one another along the major horizontal diameter of said tank.

7. The circuit breaker of claim 6 wherein said first and second capacitors have a value to appreciably lower the initial rate of rise of the recovery voltage transient imposed across said interrupter following a fault current interruption.

* l l l l 

1. In a high voltage circuit breaker: a grounded support tank filled with dielectric gas at some pressure greater than atmospheric pressure; said tank having a generally flattened spherical shape; said tank having an interior bottom and a vertical axis; circuit interrupter support means secured to said interior bottom of said tank and being generally laterally symmetrically disposed around said vertical axis of said tank; circuit interrupter means supported on the top of said support means and electrically insulated from said tank; said circuit interrupter means including at least four series-connected interrupters, and voltage distributing impedances disposed within said tank and connected in parallel with at least selected ones of said at least four series-connected interrupters; first and second terminal bushings disposed symmetrically relative to said vertical axis of said tank and extending through and secured to laterally displaced regions of the top of said tank; said terminal bushings having conductive studs electrically insulated from said tank and electrically connected to said circuit interrupter means; and first and second capacitors for control of transient recovery voltage physically mounted within opposite side regions of said tank and laterally displaced from said circuit interrupter support means and said circuit interrupter means; each of said capacitors having first and second terminals; said first terminal of each of said capacitors being disposed adjacent to and being electrically connected to respective interior portions of said tank; said second terminal of each of said capacitors being electrically connected to said conductive studs of said first and second terminal bushings, respectively.
 2. The circuit breaker of claim 1 wherein said first and second capacitors are each elongated tubular bodies which are vertically disposed within said tank.
 3. The circuit breaker of claim 1 wherein said first and second capacitors have a value to appreciably lower thE initial rate of rise of the recovery voltage transient imposed across said interrupter means following a fault current interruption.
 4. The circuit breaker of claim 1 wherein said circuit interrupter support means includes at least two parallel vertical tubular insulation pedestals which are spaced from one another along the major horizontal diameter of said tank.
 5. The circuit breaker of claim 2 wherein said first and second capacitors have a value to appreciably lower the initial rate of rise of the recovery voltage transient imposed across said interrupter means following a fault current interruption.
 6. The circuit breaker of claim 2 wherein said circuit interrupter support means includes at least two parallel vertical tubular insulation pedestals which are spaced from one another along the major horizontal diameter of said tank.
 7. The circuit breaker of claim 6 wherein said first and second capacitors have a value to appreciably lower the initial rate of rise of the recovery voltage transient imposed across said interrupter following a fault current interruption. 